Gas cooker FAN always running!!

[psarinuk]

Hi,

I inherited a gas cooker with my house 7 years ago. Its a standard cooker with 4 hobs and a grill and a oven.
There is an extractor fan that kicks in after a few minutes of use of GRILL and OVEN and it TURNS OFF automatically as well (Normally a few minutes after the grill/ oven is turned off).

Lately the fan has started to run all the time as soon as the MAINS POWER is connected, regardless of OVEN/ GRILL running or not.

The only way to turn it off is to turn off the mains after use, which we never used to do before. I suspect there is a thermostat failure?

Please refer to the attached pic from the cooker's backside. Is it possible to carry out a DIY fix? Any advice is welcome.
Thanks.

 

[Jackrae]

It may be a sticky switch on the grill door. Some (most ?) are designed to run the fan when the grill door is open, but if the switch is sticking, this will cause the fan to run continuously.

 

[psarinuk]

Hi Jackrae,

There does not seem to be any switch for the grill or the oven door (only a catch for the oven door).

Also if you read my description again, the fan used to come on when the oven or grill (separate compartments) used to get warm, not when their doors were opened.

The fan would turn off automatically some time after oven or grill was turned off.

 

[jj4091]

I suspect there is a thermostat failure?

Please refer to the attached pic from the cooker's backside. Is it possible to carry out a DIY fix? Any advice is welcome.
Thanks.

It depends how confident & competent you are. It does sound like it's possibly a sticking stat., do you have a multi-meter?

 

[Terox]

It looks like a Stoves/NewWorld build, looking at the photo

This is likely to be operated by a "Thermal Cut In" switch
It should be open circuit when cold and closed circuit when it reaches it's trigger temperature. The component will be a little button stat fitted above the grill, accessible by removing the hotplate.

You will need a multimeter to test for continuity in its cold state.

Turn the power off
Remove 1 wire from it
Check across the terminals, should be open circuit

Work should be carried out by a gas safe engineer only

 

[psarinuk]

Hi,

I do have a multi-meter.

Exact location of thermal cut-in switch would be beneficial to know.

This a gas cooker with seperate grill and oven compartments, so where is the hotplate? (I've uploaded a front pic)

Would removing the backplate help to locate the thermal switch?

Thanks.

[/url][/img]

 

[Terox]

The hotplate is the white top that the hob burners and pan stands sit on. There are 2 plastic buttons fitted along each side of the hotplate. These will need to be removed to raise the hotplate up. You will then be able to hinge the hotplate up at the front end. Support it by using one of the pan stands vertically at one side.

You cannot get access to the Thermal switch by removing the backplate. The thermal switch is sat at the same level as the base of the cooling fan. The backplate only allows access to parts lower than that

Underneath the hotplate is a hollow, approximately 6 to 8" deep. At the base of the hollow is a flat sheet of mild steel that sits across the entire width and length of the hollow forming a base for it. The Thermal switch is screwed to that.

You will find a similar component on there which is a grill/Top oven thermal cut out. (This will be centre front and protected by a yellow silicon boot) This is a safety cut out if the grill, top oven gets too hot because of a failed cooling fan or oven thermostat. This will be closed circuit when cold, working the opposite to the Thermal cut in that operates the cooling fan. It will not be inline with the cooling fan and will operate at around 100 to 150 Deg C, whereas the Fan cut in should operate at the 60 to 70 Deg C mark.. Each thermal switch should have an operating temperature stamped on it, either at the side or underneath it Thought i'd best let you know how to tell the two apart

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Side note

When it was working properly before the fault occurred, did the cooling fan come on as soon as the grill door was opened or did it come on a few minutes after the grill was lit ?

If it used to come on as soon as the grill door was opened, it also have a microswitch on the hinge bar, which you can get too by removing the side panel. (Normally the right side as you are looking at the front of the appliance) Open circuit when door closed, closed circuit when open

 

[psarinuk]

Thanks Terox,

That was well explained.

When it was working properly before, the cooling fan used to come on a few minutes after the grill was lit, it was not related to grill door I think.

Now I need to open the grill and get the thermal cut in switch. Its the one that is inline with the fan and has a temperature rating of 60 to 70 deg C marked on it.

Would it be worth getting the replacement part (thermal cut in switch) beforehand? Any idea where to get it from?

Thanks.

 

[Terox]

Thanks Terox,

That was well explained.

When it was working properly before, the cooling fan used to come on a few minutes after the grill was lit, it was not related to grill door I think.

Now I need to open the grill and get the thermal cut in switch. Its the one that is inline with the fan and has a temperature rating of 60 to 70 deg C marked on it.

Would it be worth getting the replacement part (thermal cut in switch) beforehand? Any idea where to get it from?

Thanks.

Firstly I would check the thermal switch, just to make sure it is that (99.9% sure).
It should only take you a few minutes to remove the "plugs" for the hotplate, which depending on how old the appliance is can be one of two types, both of which are plastic

"Plug Type A" has a flatpoint screwdriver slot in it, turn it 1 quarter and then prize it out with a small flatpoint screwdriver

"Plug Type B" is made up of 2 parts, easily recognised because it has a philips, cross head type screwdriver fitting

It has an inner "screw" which if it doesnt unscrew using a screwdriver needs to be prised out by shoving a small flatpoint screwdriver behind the head and teasing it out. Once you get it a little out you can pull the thing out. If you break the head of the plastic screw, push it through to the inside with the small flat point and when you refit it,m put a metal self tapping screw in its place.
When you have achieved this, the second part, main body of the plug just pulls out

Having removed all 4 plugs, just raise the hotplate up at the front, you may have to wiggle it a bit until its sitting at around a 45 degree angle




You can buy the thermal switch direct from Stoves (GDHA). They have a spares line. You will need to quote the product code, it will either start with 05 for older products or 44444 for newer appliances. This number will uniquely identify that appliance

You will find the product code on the data badge. Stoves normally have 2, one on the back and one on the front frame which is normally behind the grill door or the main oven door. The actual cost of these components is normally a few quid, how much the manufacturer will charge you is anyones guess. Get the part number of their sales line and do a google search, see if you can get it cheaper from an online spares retailer before you buy it from them

 

[psarinuk]

Hi Terox,

I managed to open up the cooker hotplate but could not find the thermal cut-in swtich (60-70 deg rating) as you advised.

I am attaching a pic here.

I did find the thermal cut out switch that was enclosed in yellow rubber towards the center front.

Please advise where is the cut in switch?

Thanks.

[/url][/img]

 

[Terox]

The two wires that are coming out of the back near the cooling fan. (Blue and white). They are the cooling fan wires.
Trace them
One is likely to go to the terminal block (Probably the blue one). The other one will be connected to the fan cut in. This may very well be the Thermal switch protected by the yellow boot. If it doesnt go to that switch then the only other likely location for it is on the back of the cavity,, accesible by removing the rear service panel (Shiny tin back panel).

Trace the white wire, that should lead you to it.

If you are having problems, post the Product Number (Begins with either 05 or 444 and the serial number (Which will tell me the date of production) I'll take a look at the wiring diagram for you.

 

[psarinuk]

Hi Terox,

I've not managed to open the cooker again. The cooker is at my mum's place and I've not really had much time yet.

However I've the part number and serial number for you.
Model number: 050531036
Serial number: 10354897

As you said, Its a STOVES make, model is NEWHOME.

Can you please help me with more precise instruction regarding the faulty thermal switch.

Thank you so much.

 

[psarinuk]

Hi,

I am attaching another pic after opening the cooker. The white wire from fan is attached to the thermal switch at center-front that is enclosed in yellow rubber. The fan stopped when the white wire was removed from this switch.

The blue wire from fan is going into a hole, don't know where, possibly accessible via back plate.

Do I need to order the switch in yellow boot?

Please refer to this image and advise.

Thanks.

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Uploaded with ImageShack.us[/img]

 

[Terox]

if the fan is connected to that switch AND you have checked with your multiimeter that the switch is "Closed Circuit", eg electricity can pass from one terminal to the other. It should be the opposite in a cold state.

It can't really be anything else.

The blue wire will be going to the terminal block

Stoves have a direct sales line. Quote the model number and ask for the "Cooling Fan thermal switch"

At a guess should only be a few pounds

 

[psarinuk]

Hi Terox,

Ordered new switch online and installed. It seems to be working fine now.

Many thanks for your help once again.
Best regards.